1. Field of the Invention
The present invention relates to an apparatus for preventing blurred pictures in a camera using an angular acceleration sensor. The invention also relates generally to an angular acceleration sensor.
2. Description of the Related Art
Upon taking a picture with a camera held by a photographer, undesirable movement of the optical axis of the camera tends to occur due to camera-shake, as when the picture composition is incomplete, when a dark subject is taken at a slow shutter speed, or when a moving photographer takes a picture. The camera-shake results in a blurred picture. The camera-shake, which largely depends on a photographer's skill, can be eliminated to some extent by increasing the full-open aperture (decreasing the F-number) of lenses or a film sensitivity, thereby to increase the shutter speed.
In view of limits to access to such a camera-shake from a view point of software (photographer's skill) or hardware (decreasing F-number of lenses or increasing film sensitivity), apparatus for correcting blurred pictures in a camera has been proposed, in which, when a movement of the optical axis takes place due to camera-shake etc., a correcting lens is moved in a direction opposite to the direction of the movement of the optical axis to cancel the movement of the optical axis, thereby eliminating image blur.
In such a proposed blurred image correcting apparatus, it is necessary to detect angular deviation of the optical axis. To this end, a pair of angular acceleration sensors which are spaced from one another in the optical axis direction are provided to detect angular acceleration, as disclosed for example in Japanese Unexamined Patent Publication No. 62-47012. However, the incorporation of two such angular acceleration sensors into a camera to detect angular deviation (movement) in one direction makes the camera impracticable, expensive and complicated. This is one of the reasons that no camera having therein an image blur correcting apparatus is realized and yet available on the market. Furthermore, a conventional acceleration sensor is inevitably influenced by the acceleration of gravity. Accordingly, in order to actually incorporate the blurred image correcting apparatus into a camera, it is necessary to realize a smaller and more efficient angular acceleration sensor.